737 MAX Flight Crew Operations Manual
Flight Management, Navigation -
FMC Cruise
MN-FLT-OH-201
11.42.39
Navigation Options (NAV OPTIONS)
The FMC normally rejects the use of navaids that are not suitable for navigation.
However, when the aircrew is aware that unreliable navaids exist (either by
NOTAM, ATC, etc.) they should manually exclude these navaids from the FMCs
navigation solution. This will prevent the possibility of incorrect position
calculations and maximize the FMCs reliability. This is accomplished through the
NAV OPTIONS page.
Access to the NAV OPTIONS page may be gained by selecting the NAV
OPTIONS prompt on the REF NAV DATA page or by selecting NEXT or PREV
PAGE on the NAV STATUS page.
1
DME/VOR INHIBIT
Enter the identifier of up to two VOR/DME, VORTAC, or DME stations that must
not be used for FMC position updates.
Entries are blanked at flight completion.
Deleting or overwriting removes a previous inhibit.
The FMC normally uses DME from two different ground stations to update its
position solution. When two DME stations are not available, the FMC reverts to
single station radial-DME updating to determine position. Only two of the four
inhibit entries are utilized at any one time depending upon which update mode the
FMC is operating in. The DME INHIBIT entries are excluded from the FMCs
update solution whenever the FMC is updating from two DME stations. The VOR
INHIBIT entries are excluded from the FMCs update solution whenever the FMC
is radial-DME updating.
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March 1, 2021
